The bearing of a wheel hub, particularly the outer race of the bearing must be axially restrained to the vehicle suspension standard or knuckle, to avoid the risk of the bearing coming off under the effect of axial loads acting on the bearing during operation.
At present there are known several fixing systems, adapted for different arrangements.
According to a first known system, firstly the bearing is fitted into a corresponding circular seat obtained in the knuckle and pushed against an axially inner shoulder. Secondly, a seeger ring is snap fitted in a circumferential groove at the entrance of the circular seat so as to axially retain the outer race of the bearing. Then, the wheel hub is inserted through the inner race of the bearing and secured in known manner to the constant velocity joint.
In other cases, it is preferred to firstly pre-assemble the bearing to the wheel hub and then insert and fix such a unit to the knuckle. When this route is followed, then it is not possible or practical to fit a seeger to stop axial movement of the bearing because the pre-assembled hub would render this operation difficult. Generally, the outer race of the bearing is forcefully fitted into the knuckle with some interference. However, this provision can not prevent the bearing from slipping outwardly under the action of loads exceeding a certain threshold.